Lossy waveguides with arbitrary boundary contour and material distribution

An extension of a known finite difference method for the system of differential equations of longitudinally homogeneous waveguides is presented. The method makes it possible to calculate the eigenmodes and complex propagation constants of lossy waveguides of arbitrary boundary contour and arbitrary transversal inhomogeneous distribution of material properties (permittivity, permeability, and conductivity). A novel feature of the method is the admissibility of triangular domains, which removes one of the disadvantages of the finite-difference method in comparison with the finite element method.